System and process for continuous and controlled production of metal-organic frameworks and metal-organic framework composites

ABSTRACT

A MOF production system and method of making are detailed for continuous and controlled synthesis of MOFs and MOF composites. The system can provide optimized yields of MOFs and MOF composites greater than or equal to 95%.

STATEMENT REGARDING RIGHTS TO INVENTION MADE UNDER FEDERALLY-SPONSOREDRESEARCH AND DEVELOPMENT

This invention was made with Government support under ContractDE-AC05-76RL01830 awarded by the U.S. Department of Energy. TheGovernment has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates generally to Metal-Organic Frameworks.More particularly, systems and methods for continuous and controlledproduction of Metal-Organic Frameworks and Metal-Organic FrameworksComposites.

BACKGROUND OF THE INVENTION

Metal-Organic Frameworks (MOFs) have attracted significant attentionowing to their structural and chemical diversity. MOFs are compoundswith a porous crystalline structure that contain metal ions thatcross-link with organic linkers in various coordination networks thatform one-, two-, or three-dimensional structures. MOFs have a highsurface area, large pore volumes, and various pore dimensions andtopologies that make MOFs superior to other porous materials for avariety of applications. MOFs are conventionally synthesized usingliquid batch methods in various solvents or aqueous solvents underso-called solvo-thermal or hydro-thermal conditions. Many MOFs areprepared in pure N,N-diethylformamide (DEF) or N,N-dimethylformamide(DMF) or a combination of solvents that include DMF which decompose atreaction temperatures between 50° C. and 250° C. generating an aminebase that deprotonates functionalities of the organic linker to form theselected metal-organic framework (MOF).

However, conventional batch synthesis of MOFs has well-known andsignificant disadvantages. It is well known, for example, that liquidbatch synthesis of MOFs produces partially formed products, unreactedproducts, and contaminates that cannot be removed from the solvents.Contamination of solvents and liquid precursor materials means solventscannot be reused and must be replaced after every production run.Solvents alone account for nearly half of the total cost of a MOFproduct presently. Thus, following separation from the batch liquid, MOFcrystals must be activated prior to use using a multi-step solventexchange process that removes contaminants, partially reacted (orunreacted) products, and high-boiling solvents from the pores of theresulting MOFs—a slow and costly procedure.

Another disadvantage of conventional batch synthesis is the productionof low-purity MOFs. Only a small fraction of a desired MOF product isproduced. And, presence of secondary or interpenetration frameworks canexist within pores of a first framework, which are difficult to detect.Presence of secondary frameworks can block existing pores which affectsproperties of the resulting MOF. In addition, batch methods do notoperate continuously, and have limited or no scalability, and as suchare less likely to be cost-effective methods for MOF production. Batchmethods used to produce MOF particles are also small or undersized,which limits potential applications or requires expensivepost-processing to correct and are typically also very slow. Typicalsynthesis times are in excess of 24 hours on average and can be as longas 3 weeks or more.

Various methods have been proposed in the literature for combining MOFswith other functional matrix materials to form new multi-functional MOFcomposites that exhibit desired properties in order to broaden potentialapplications. However, controlling integration of the various anddisparate individual components in suitable MOF composites is stillundergoing. Thus, despite their tremendous potential, deployment of MOFsin commercial or industrial applications is currently limited by a lackof technologies and processes that permit synthesis and activation ofthese materials in suitable quantities, at desired quality and at coststhat would make industrial applications feasible. New systems andprocesses are needed that address the various limitations ofconventional syntheses and permit production of Metal Organic Frameworks(MOFs) and MOF composites on a large scale. The present inventionaddresses these needs.

SUMMARY OF THE INVENTION

The present invention provides a system and method for efficientscalable synthesis of Metal-Organic Frameworks (MOFs) materialsincluding and MOF composites. In one embodiment the method for makingMetal Organic Framework (MOF) materials including MOF composites, themethod includes the step of injecting aerosolized MOF precursors into afluidized bed reactor at a preselected temperature. Preferably this isdone simultaneously and the combination of aerosolized dispersion of theMOF precursor into a fluid volume at a preselected temperature maintainsconsistency in particle formation which can then form the seeds forfurther growth. At the end of the desired MOF synthesis the temperaturewithin the reactor can be raised to evaporate the residual solvent anddensify the selected MOF products. In addition to providing effectiveand efficient MOF products the present invention also can be configuredto recapture the MOF solvents which can then be recirculated and reused.

The simultaneous evaporation of the solvent within the fluidized bedreactor coupled with capture of the evaporated solvent as well as theultrasonic aerosolization of the MOF precursors, and the fluidization ofthe MOF materials provide advantages in formation over the prior art.When the desired synthesis is complete the temperature in the reactorcan be raised to remove any remaining solvents and densify the newlyformed MOF material. These solvents can then be reused and recycled.Greater efficiencies can be obtained by continuously performing themethod by introducing additional aerosolized MOF precursor dropletscontinuously into the fluid volume, while simultaneously heating,sonicating and recapturing solvents. This can be coupled to processesfor removing materials or leaving them within the reactor in order fortheir size to increase. The present invention utilizes many MOFprecursor materials. MOF precursors may include one or more metalsselected from the group consisting of: Ti, V, Cr, Mn, Fe, Co, Ni, Cu,Zn, Y, Zr, Nb, Mo, Tc, Ru, Os, Rh, Pd, Ag, Au, Cd, Ir, Pt. andcombinations thereof.

In addition the MOF precursors may include an organic linker selectedfrom an aryl organic acid; an aryl alcohol; an aryl carboxylic acid; anaryl hydroxyl carboxylic acid; di-substitution products,tri-substitution products, and tetra-substitution products thereof; orcombinations thereof. The formed MOF or MOF composites are preferablybetween about 50 μm to about 1500 μm in size. The method of the presentinvention is also performed in an inventive system. In one embodiment ofthe invention the system includes a MOF production reactor that definesa fluidized bed reaction chamber configured to receive a plume ofaerosolized MOF precursor droplets in a carrier gas therein for a timesufficient to form solid particles of the MOF or MOF composite of aselected size therein. The system may also include a heating device toalternatively raise and lower the temperature within the reactionchamber, an ultrasonic aerosolization device, a de-entrainment chamberconfigured to remove and collect solvents from the aerosolized MOFprecursor droplets, a separation and recirculation device configured tocollect the solid particles at the selected size from the MOF productionreactor and to return the solid particles smaller that a preselectedsize back into the reaction chamber, and other pieces to assist in MOFformation. These items may have various names including a MOF productionreactor (MPR) that includes an aerosolization, condensation, andevaporation (ACE) chamber configured to suspend a plume of aerosolizedliquid MOF precursor droplets in a carrier gas and to circulate same inselected directions relative to the flow of the carrier gas, forexample, parallel, orthogonal, or other selected angles at a selectedtemperature above ambient for a time sufficient to form solid particlesof the MOF or MOF composite of a selected size therein. The MPR includesa MOF precursor solution introduction system that delivers MOF precursorsolutions in a carrier gas into the MPR as a plume of aerosolized liquiddroplets. The MPR further includes a de-entrainment (De-MOF) chamberconfigured to remove solvents from the aerosolized MOF precursordroplets therein that yields the MOFs and MOF composites formed in theMPR. Recovered solvents may then be recycled back into the MPR.

In one embodiment the method may include circulating the plume ofaerosolized liquid droplets in the reaction chamber in a directiondefined at a selected angle relative to the direction of flow of thecarrier gas. For example, in some embodiments, the plume of aerosolizedMOF precursor droplets is circulated in the fluid volume of the reactionchamber in a direction parallel to the direction of flow of the carriergas. In some embodiments, the plume of aerosolized MOF precursordroplets is circulated in the fluid volume of the reaction chamber in adirection orthogonal to the direction of flow of the carrier gas.Carrier gases may include an inert gas or a mixture of an inert gas andone or more solvent vapors.

The method steps including introducing steps and circulating steps maybe performed iteratively, for example, by introducing a fresh quantityof aerosolized MOF precursor droplets of a same or different MOFprecursor solution continuously into the fluid volume of the reactionchamber to increase the size of the resulting solid particles of the MOFor MOF composite.

Forming solid MOFs and MOF composites in the ACE chamber can includecondensing aerosolized MOF precursor droplets after releasing solventstherefrom at the reaction temperature to form seed particles of the MOFor MOF composite of a selected size. Size of the seed particles istypically about one micrometer. Solid seed particles formed in the ACEchamber provide sites for deposition and condensation of additionalaerosolized MOF precursor droplets thereon of a same or different MOFprecursor solution which increase the size of MOFs and MOF compositesformed therein. Thus, in some embodiments, seed particles may compriseparticles of a selected size, as detailed herein. In other embodiments,seed particles may comprise particles of non-MOF materials including,but not limited to, for example, metals, metal oxides, carbon, graphene,silicates, and other materials of a selected size that can also act assupports for growth of aerosolized MOF precursor droplets in the MPR, asdetailed further herein. MOFs and MOF composites may be collected whenselected particle sizes are reached.

Formation of MOFs and MOF composites can include removing(de-entraining) solvents as clean vapors from the MOF precursor aerosoldroplets or from newly formed MOFs and MOF composites which can then becollected and recycled back to the MPR in various forms. Recycling thesolvents can include introducing same into the MPR in the form of, forexample, MOF precursor solutions, as make-up solvents, or as freesolvents. The method may include forming solid particles of the MOF orMOF composites continuously.

In some embodiments, forming the solid particles includes a time offormation of at least about 1 minute. In some embodiments, forming thesolid particles includes a time of formation of less than about 10minutes. In some embodiments, forming the solid particles includes atime of formation of less than or equal to about 10 hours. In someembodiments, particles of the resulting MOFs or MOF composites arepreferably selected between about 50 μm to about 1500 μm. The method mayfurther include releasing the solid particles from the reaction chamberat the selected size to collect same and returning solid particles withsizes below the selected size back into the reaction chamber to increasethe size thereof. In various embodiments, the method yields solid MOFsas products that are MOF composites, as detailed herein.

The present invention yields MOFs and MOF composites that are activatedimmediately upon formation without need for a solvent pre-treatment stepto remove contaminates. Yields of MOFs and MOF composites are scalable.Optimized yields are greater than or equal to about 95%. For example, insome embodiments, yields are 99%.

The purpose of the foregoing abstract is to enable the United StatesPatent and Trademark Office and the public generally, especially thescientists, engineers, and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. The abstract is neither intended to define theinvention of the application, which is measured by the claims, nor is itintended to be limiting as to the scope of the invention in any way.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sample system for production of MOFs and MOF composites.

FIG. 2 illustrates an exemplary process for continuous production ofMOFs and MOF composites, according to one embodiment of the process ofthe present invention.

FIG. 3 compares XRD results for an exemplary pure MOF synthesized inaccordance with the present invention against a MOF synthesized byconventional liquid batch processing.

FIG. 4 is an SEM image of an exemplary pure MOF synthesized inaccordance with the present invention

FIG. 5 compares fractions of particles with selected sizes for anexemplary MOF synthesized in accordance with the present inventionagainst a MOF synthesized by conventional liquid batch processing.

FIG. 6 compares distribution of particle sizes for an exemplary MOF ofthe present invention against a MOF product synthesized by conventionalliquid batch processing.

FIG. 7A is a pictograph illustrating a layered structure of an exemplarycore-shell MOF composite of the present invention.

FIGS. 7B-7D show XRD results for the MOF composite of FIG. 7A.

FIG. 7E is an SEM image of the exemplary core-shell MOF composite ofFIG. 7A.

FIGS. 7F-7G show EDX results for components of the core-shell MOFcomposite of FIG. 7A.

FIG. 8A is a pictograph illustrating a layered structure of anotherexemplary core-shell MOF composite of the present invention.

FIG. 8B shows XRD results for the MOF composite of FIG. 8A.

FIG. 8C is an SEM image of the core-shell MOF composite FIG. 8A.

FIG. 8D shows EDX results for the MOF composite of FIG. 8A.

FIG. 9 shows EDX results for yet another exemplary core-shell MOFcomposite of the present invention.

FIG. 10A is an SEM image of still yet another exemplary core-shell MOFcomposite of the present invention.

FIG. 10B presents EDX results for the core-shell MOF composite of FIG.10A.

FIG. 11A shows PXRD results for an exemplary mixed-metal MOF compositeof the present invention and pure metal MOFs from which the composite isconstructed.

FIG. 11B is an SEM image of the mixed-metal MOF composite of FIG. 11A.

FIGS. 11C-11D show electronic mapping images for each of the metals ofthe mixed-metal MOF composite of FIG. 11A.

FIG. 11E presents EDX results for the mixed-metal MOF composite of FIG.11A.

FIG. 12 compares water sorption capacities for an exemplary MOF of thepresent invention and a MOF synthesized by conventional liquid batchprocessing.

FIG. 13 compares gas sorption capacities for an exemplary MOF of thepresent invention and a MOF synthesized by conventional liquid batchprocessing.

DETAILED DESCRIPTION

A system and process are detailed for continuous and controlledproduction of MOFs and MOF composites. The present invention overcomespreviously unresolved problems, disadvantages, and limitations ofconventional liquid batch processing including scalability, time toproduce, low yields, low purity, lack of solvent recovery and recycling,activation, performance, and cost. In the following description,embodiments of the present invention are shown and described by way ofillustration of the best mode contemplated for carrying out theinvention. It will be apparent that the invention may include variousmodifications and alternative constructions. The present invention isintended to cover all such modifications, alternative constructions, andequivalents falling within the spirit and scope of the invention asdefined in the claims. Accordingly, the description of the preferredembodiments should be seen as illustrative only and not limiting.

FIG. 1 shows one exemplary embodiment of a MOF production system 100that allows for continuous and controlled production of MOFs and MOFcomposites as described in the disclosure. In this embodiment of theinvention the system 100 includes a generally cylindrical MOF productionreactor (MPR) 25 having a body that defines and internal volumesufficient to hold a fluidized bed reactor and to allow various methodsteps to occur. The capability and dimension of the internal volume isscalable to allow for scaled production of MOFs and MOF composites. Inthis exemplary embodiment, the MPR 25 body is a stainless steel vesselthat defines an internal volume of ˜5 liters. Within the MPR 25 aportion of the volume, called the ACE chamber 24 provides a location foraerosolization and condensation of MOF precursor solutions andevaporation of solvents to occur. In the illustrated embodiment this ACEchamber 24 includes a height (length) of about 24 inches (60.96 cm), awidth of about 2 inches (5.1 cm). MOF precursor solutions in a carriergas form a plume of aerosolized liquid droplets and enter into the ACEchamber through the MOF precursor solution injection system 10.Preferably the ACE chamber contains a fluid into which the MOFprecursors are enveloped and which assists to maintain generaluniformity among the size of the solvent droplets. As the MOF precursorsenter into the ACE chamber a preselected elevated temperature evaporatesthe solvents from the aerosolized droplets at the selected reactiontemperature which condenses the solid MOF seed particles. As additionalMOF precursors are added to the ACE chamber the MOF seed particlescontinue to grow by continued condensation of newly added aerosoldroplets of the MOF precursor solution onto existing seed particles,which increases the size of the MOF particles in the MPR. A moredetailed drawing of this is shown in FIG. 2.

The evaporated solvents are released as clean vapors through an outlet2. Unlike other systems these solvents can be recovered downstream andrecycled again into the system. In the operation of the exemplaryembodiment, 80% or more of solvents used in precursor solutions wererecovered and recycled.

The introduction system 10 introduces aerosolized MOF precursorsolutions into the ACE chamber (zone) 24 in an inert carrier gas. Theintroduction system combines the aerosolized MOF precursors, a carriergas and gas/solvent mixtures from each of their respective sources. Inthe example shown this would include the MOF precursor supply 6, thesolvent supply 16 and the solvent condenser 30 and the carrier gassupply 14. These are all plumbed and interoperably connected to anintroduction system 10 that includes one or more introduction devices 4that aerosolize MOF precursor solutions introduced into MPR 25 as aplume of aerosolized liquid droplets (aerosols) of preselected sizes,preferably ranging from anywhere from about 500 μm to about 2000 μm.Examples of such introduction devices 4 include, but are not limited tonebulizers; atomizers; misters; injectors; specialized nozzles, nuzzlesand other similar devices and combinations. In the exemplary embodimentan ultrasonic aerosolizer was utilized to create and maintainaerosolized droplets.

The introduction system 10 utilizes one or more of such introductiondevices 4 to introduce MOF precursor solutions into the MPR. Dependingupon the needs of the user these ports may be variously configured tointroduce a single MOF precursor solution into the MPR for synthesis ofa single type of MOF, or multiple and different MOF precursor solutionsinto the MPR for synthesis of various MOF composites detailed herein. Inthe present illustrated embodiment the introduction system 10 is shownwith three introduction devices 4 positioned at selected locations alongthe length of the MPR to create and control desired circulation patternsof MOF precursor solutions into the MPR. While this exemplaryarrangement is shown it is not limiting and MOF precursor solutions canbe introduced into the MPR in various directions and patterns dependingupon the needs of the user and as detailed further herein. In theillustrated embodiment a distribution plate 20 is also a part of theintroduction system and functions to assist in the delivery of a carriergas and gas-solvent mixtures uniformly through the MPR. The distributionplate 20 may include a number of inlets through which MOF precursorsolutions and carrier gasses are passed into the chamber and acirculating pattern of aerosolized liquid droplets are created andmaintained.

In the exemplary embodiment, MOF precursor solution is introduced in adirection parallel to the flow of the carrier gas or gas-solventmixture, for example, through the bottom or top of the reactor at aselected flow rate. However, direction is not limited, as shown. Invarious embodiments, MOF precursor solution is introduced in variousdirections at angles selected between about 0 degrees and about 180degrees relative to the flow of the carrier gas or the gas-solventmixture to create various circulation patterns for the aerosolizeddroplets of MOF precursor solution in MPR. Carrier gases used in concertwith the present invention may be either inert or reactive and recoveredsolvent vapors and recovered carrier gases may be used to form a part ofthe carrier gas portion.

In the exemplary embodiment, flow rates for the carrier gas are selectedfrom about 0.5 standard cubic feet per minute (scfm) to about 5.0 scfm,with a typical rate of about 2.0 scfm. Gas flow rates are selected thatsuspend and circulate MOF precursor solutions in ACE chamber in MPR. Gasflow rates are typically adjusted depending upon the size of the MOFparticles. Preferred carrier gas flow rates are between about 5 times toabout 10 times the minimum velocity needed to suspend MOF precursorsolutions in the MPR. Higher velocities provide better suspension of MOFprecursor solutions for continuous production of MOF particles in theMPR for selected applications. As the MOF precursors and the carrier gaspass through the fluidized bed reactor the particles coalesce in thereactor and fluidize. The deposition of the MOF precursors on thefluidized particles form seeds from which the MOF will form and develop.When the solvent is driven off these MOF will densify and be activatedand ready for use.

In this embodiment of the invention a MOF de-entrainment chamber 26couples to and is in gas (vapor) contact with ACE chamber 24 describedpreviously. In the exemplary embodiment the de-entrainment chamber 26 isconfigured to decelerate MOF particles formed in ACE chamber particlesso they are no longer suspended in the carrier gas. Deceleration of MOFparticles serves to separate (de-entrain) MOF particles from solventvapors and the carrier gas before the solvents and carrier gas exit theMPR. In this illustrated embodiment the velocity of circulating MOFparticles reaching the de-entrainment chamber 26 decreases as the squareof the cross-sectional area. In the exemplary embodiment, velocitydecreases by a factor of [36÷9] or four (4) times compared to thevelocity of MOF particles circulating in ACE chamber 24. De-entrainedMOF particles drop, for example, to the bottom of ACE chamber 24 forcollection when the MOF particles reach a selected or desired size, orcontinue to circulate and grow in ACE chamber, as detailed furtherherein.

MOF de-entrainment chamber 26 includes a diameter dimension that isgenerally 3 to 10 times larger than the diameter dimension of ACEchamber 24. Dimensions are selected to provide a selected density of,and minimum diameter for, MOF particles in MPR. In the exemplaryembodiment, de-entrainment chamber 26 includes a height (length)dimension of about 12 inches (30.48 cm), a width dimension of about 6inches (15.24 cm), and a wall thickness of about 0.25 inches (0.635 cm),respectively. Dimensions and internal volumes are scalable permittingscaled production of MOFs and MOF composites.

In some embodiments, solvents released as vapors from de-entrainmentchamber 26 are condensed in a condenser 30 positioned downstream fromMPR 25 into their liquid form. Condensed and recovered solvents may bereturned through a line controlled by a control valve 32 (e.g., a 3-waycontrol valve) and delivered, recirculated, or fed back into MPR 25 upondemand through introduction system 10. In some embodiments the recoveredsolvents may be stored in a solvent reservoir 6, and then be mixed intonew MOF precursor solutions, or be recycled back into MPR as a make-upsolvent, or otherwise re-introduced back into the MPR to minimize thequantity of solvents needed for continuous operation. In addition to therecovery of solvents, recovered carrier gases can also be reintroducedinto MPR. In some embodiments, system 100 further includes a separationand recirculation device 34 that couples to ACE chamber 24, and assiststo control and select the sizes of MOF particles formed in MPR 25. Inthis illustrated embodiment a cyclone separator is shown. Such devicesfind particular utility in for example, for industrial applications.

In the exemplary embodiment, separation device 34 separates streams ofparticles into two streams. In a first stream, MOF particles of apreselected or selected size (e.g., “right-sized” or “over-sized”particles) are removed from ACE chamber 24 for collection. In a secondstream, MOF particles with a size below the selected size (termed“fines” or “under-sized” particles) are returned to ACE chamber 24 forcontinued growth via deposition of MOF precursors until a desired sizeor characteristic is reached. While in this exemplary embodiment thisseparation device 34 is positioned external to the MPR 25, but theinvention is not intended to be limited thereto, such a device could bealternatively integrated within the ACE chamber 24. In some embodimentsan in-line filter 36 positioned downstream from outlet 2 can be utilizedto remove any fines or particulates if released in solvents from theMPR. However, filter 36 is an optional component given the cleandistillation of solvents from MPR 25.

System 100 may also include a heat exchanger 38 that heats carrier gasesor preheats condensed solvents recovered from MPR 25 prior to re-entryback into the MPR. Gases, solvents, and MOF precursor solutions may bedelivered and introduced into the MPR at selected pressures in concertwith one or more pumps 40 such as, e.g., HPLC pumps or other pumpingmeans known to those of ordinary skill in the art. No limitations areintended. The system 100 may also include a computer control system tocontrol the systems including the MOF precursor introduction system 10,opening and closing of outlets 2 and inlets 22, flow of solvents intoand out of solvent condenser 30, opening and closing of control valve32, flows into and out of heat exchanger 38, and recirculation of MOFparticles in and out of separation and recirculation device 34.

FIG. 2 illustrates an exemplary process for continuous production ofMOFs and MOF composites at superior yields. The process includessuspending a plume of aerosolized liquid droplets (aerosols) of a MOFprecursor solution of a preselected size in a carrier gas in the vaporphase at a selected temperature in the ACE chamber (described previouslyin reference to FIG. 1) to form MOFs and MOF composites. As shown in thefigure, MOF precursor solution can be introduced by introduction system(FIG. 1) into the ACE chamber (FIG. 1) in the MPR in various or selecteddirections with introduction devices 4 such as a nozzle properlypositioned within the MPR. Introduction of MOF precursor solutionsgenerates a plume of aerosolized precursor droplets of a desired orselected size. Aerosolized MOF precursor droplets are suspended in thecarrier gas and circulated to maintain a uniform distribution of MOFprecursor droplets in the fluidized bed reactor chamber. As the gassescirculate through the chamber fluidization occurs and this regulates theformation of the MOF materials that are developed. As this processprogresses the chemical reagents introduced in the MOF precursorsolutions coalesce in the MPR as solvents are removed from theaerosolized droplets, which yields the 3-D crystal structure of theresulting MOF or MOF composite formed in the MPR. Factors that controlproduction of MOFs and MOF composites include, but are not limited to,for example, flow rates of MOF precursor solutions, carrier gases,and/or solvents into MPR; concentrations of reactants and othercomponents in MOF precursor solutions, circulation rates of MOFaerosols; MOF particle density (p); and MOF particle sizes in MPR.

Solid MOF seed particles of typically a nanometer size will typicallyform initially. MOF seed particles continue to circulate in the MPRsuspended in the carrier gas, which permits newly aerosolized dropletsof the MOF precursor solution to condense onto the surface of theexisting seed particles and for the MOFs to grow. Subsequent evaporationof solvent solidifies the new MOF precursor solution onto the existingseed particles, which adds a new layer or additional material thatincreases the size of the existing particles forming larger solid MOFparticles. Solid MOF seed particles and larger MOF particles thus act assolid supports for continued growth of MOFs and MOF composites in theMPR. New MOF precursor solution is continuously introduced into the ACEchamber, which provides continuous production of new MOF seed particlesand controlled production of MOF particles of preselected or selectedsizes. MOF precursor solutions may have the same or differentcompositions to form a variety of different MOFs and MOF composites. MOFparticles that achieve the selected or desired particle size may becollected and removed from the ACE chamber, for example, with aseparation and recirculation device described previously in reference toFIG. 1.

FIGS. 3-6 show a variety of comparisons between the MOF products createdin the present invention and the MOF products created by prior artprocesses. FIG. 3 compares XRD results for an exemplary nickel-based MOFproduct, Ni-MOF-74, synthesized in accordance with the present inventionagainst the corresponding product produced by conventional liquid batchsynthesis. Results show the MPR-synthesized MOF product is identical tothe conventional product. However, MOF yields provided by the presentinvention are superior as discussed further herein. FIG. 4 shows an SEMimage of an exemplary pure MOF synthesized in accordance with thepresent invention FIG. 5 compares cumulative fractions (volume %) ofparticles of selected sizes for an exemplary MOF (i.e., Ni-MOF-74)synthesized in accordance with the present invention against aconventional batch-synthesized product. Results show MOFs of the presentinvention have a cumulative particle size significantly greater comparedto the batch synthesized product. And, sizes are selectable. Thebatch-synthesized product is not. FIG. 6 compares the distribution ofparticles of various sizes for the exemplary Ni-MOF-74 product of thepresent invention against the batch-synthesized product. Data in FIG. 6again shows that particles of the MPR-synthesized Ni-MOF-74 (i.e.,preselected or controlled) product have a mean particle size of ˜200microns compared to the mean particle size for the batch-synthesized(uncontrolled) particles of only 50 microns. In addition, Ni-MOF-74particles of the present invention do not require solvent purificationfollowing synthesis.

The reaction kinetics of the present invention are superior toconventional liquid batch processing and provide a significantadvantage. In a typical synthesis of a pure metal MOF (e.g., Ni-MOF-74),for example, the present invention forms MOF particles of a 20 micronsize in a typical time of 1 minute or better compared to 24 hours forconventional liquid batch synthesis. These exemplary MOF productionresults correspond to a surprising improvement in reaction kinetics ofat least about 1440 times, or 4 orders of magnitude. The yields of theMOFs and MOF composites are scalable. Unoptimized yields of MOFs and MOFcomposites are typically greater than or equal to about 35%, howeverwith optimization yields anywhere from 60% to 99% are possible. MOFs andMOF composites generated under this process also have a superior puritydue to an absence of reactant contamination. Again purity percentagesvary from 60% to 99% or better.

The materials, rates and conditions for operation of the presentinvention can vary widely and can be specifically tailored to meet theneeds of a particular user. The examples and information provided hereafter therefore should be understood as exemplary only and not aslimiting as to the scope of the invention. As a party of skill in theart will recognize, various alternative and modifications to the presentinvention can be made without detracting from the spirit and scope ofthe invention as set forth in the claims.

Table 1 shows exemplary parameters for synthesizing various pure metalMOFs in accordance with the present invention.

TABLE 1 Ligand: MOF Metal Salt Ratio Type Precursors [Mole:Mole] SolventMOF-74 [DHTA:metal nitrate] [1:3.3] [DMF:Ethanol:Water] (Ni, Co, [1:1:1to 15:1:1] Zn, Mn, Fe, Ti, Mg, Cu,) MOF-74 [DHTA:metal acetate] [1:2][THF:Water] (Ni, Zn, [1:1] Co, Mg, Mn, Fe, Cu) MOF-5 [TPA:Zn acetate][1:2.2] DMF IRMOF-3 [2-Amino TPA:Zn Nitrate [1:3] DMF (hexahydrate ortetrahydrate)] IRMOF-9 [4,4′-biphenyldicarboxylic [1:5.5] DMF acid:Znnitrate (hexahydrate or tetrahydrate)] MOF-177 [BTB:Zn Nitrate(hexahydrate [1:9] DEF or tetrahydrate)] MOF-180 [BTE:Zn nitrate(hexahydrate [1:16] [DEF:NMP] or tetrahydrate)] [1:1] MOF-200 [BBC:Znacetate] [1:10] [DEF:NMP] [1:1] MOF-210 [BTE:BPDC:Zn acetate] [1:2][DEF:NMP] [1:1] HKUST-1 [Benzene-1,3,5-tricarboxylic [1:2][DMF:EtOH:H₂O] acid:Cu nitrate (or Cu acetate)] [1:1:1] ZIF-8[2-methylimidazole:Zn nitrate [1:1] DMF or H₂O or (hexahydrate ortetrahydrate)] MeOH TetZB [tetrakis[4-(carboxyphenyl)- [1:1:1] [DMF]oxamethyl] methane; bipyri- dine:Zn nitrate (hexahydrate ortetrahydrate)] MOF-801 [Fumaric acid:Zr oxychloride] [1:1] [DMF:FormicAcid] [3:1] MOF-802 [Pyrazole-3,5-dicarboxylic [1:1] [DMF:Formic Acid]acide:Zr oxychloride] [1.5:1] MOF-805 [1,5-Dihydroxynaphthalene- [1:2][DMF:Formic Acid] 2,6-dicarboxylic acid:Zirconyl [5:1] chloride(octahydrate)] MOF-808 [1,3,5-benzenetricarboxylic [1:1] [DMF:FormicAcid acid:Zirconyl chloride [1:1] (octahydrate)] MOF-812[4,4′,4″,4′″-Methanetetrayltetra- [1:2] [DMF:Formic Acid] benzoicacid:Zr oxychloride] [1.5:1] MOF-841 Benzenetribenzoic acid:zirconyl[1:4] [DMF:Formic Acid] chloride (octahydrate)] [1.5:1] DUT-52-M[Napthalene-2,6-dicarboxylic [0.75:1] [DMF:Acetic Acid] (M = Zr oracid:Metal (M) chloride [15:1] Hf) (where M = Zr or Hf) DUT-67[Thiophene-2,5-dicarboxylic [2:3] [DMF:Formic Acid] acid:Zirconylchloride [1.8:1] (octahydrate)] UIO-66 [TPA:Zirconyl chloride [1:0.75]DMF (acidified)* (octahydrate)] UIO-67 [Biphenylene dicarboxylic [1:0.9]DMF (acidified)* acid:Zr chloride] UIO-68 [Triphenylene dicarboxylic[1:0.5] DMF (acidified)* acid:Zr chloride] NU-1000[1,3,6,8-tetrakis(p-benzoic [1:10] DMF acid) pyrene (H₄TBAPy):Zir- conylchloride (octahydrate)] SIM-1 [4-methyl-5- [4:1] DMFimidazolecarboxaldehyde:Zn acetate (dehydrate)] MIL-100Benzene-1,3,5-tricarboxylic [1:1.1] H₂O (Cr, Fe) acid:Cr nitrate or Fenitrate] MIL-101 (Cr) [TPA:Cr nitrate] [1:1] H₂O Bio-MOF-1[Adenine:4,4′-biphenyl [1:2.3] DMF:H₂O dicarboxylic acid:Zn acetate[6:1] (dehydrate)] ZMOFs ditopic N-donor linking agents Various DMA,DMF, other such as pyrimidine-, imidazole-, Ratios solvents, and andtetrazole-based linkers combinations of and transition metals solventsSIFSIX-3-M [metal silicofluoride:pyrazine] [1:2] MeOH (M = Co, Ni)Precursors: BBC =4,4′,4″-[benzene-1,3,5-triyl-tris(benzene-4,1-diyl)]tribenzoate; BTB =Benzene tribenzoic acid; BTE =4,4′,4″-[benzene-1,3,5-triyl-tris(ethyne-2,1-diyl)] tribenzoate; BPDC =biphenyl-4,4′-dicarboxylate; DHTA = DihydroxyTerepthalic Acid; TPA =Terepthalic Acid. Solvents: DMF = N,N-dimethylformamide; DEF =N,N-diethylfromamide; EtOH = ethanol; H₂O = water; NMP =N-Methyl-2-pyrrolidone; THF = Tetrahydrofuran. *(acidified) = 2 drops ofHCl (1M).

Other pure metal MOFs include, but are not limited, for example, NU-100;MIL-53; MIL-120; porous hexacyano materials (e.g., Prussian Blue); andmetal nitroprussides.

The method and system of the present invention can be utilized togenerate not only the MOFs discussed above but also MOF composites. Theterm MOF products as used in this application refers to both MOFs aswell as molecular structures that incorporate various chemicalcomponents introduced into the MPR in selected MOF precursor solutionsor as dry powders that are incorporated into the structure of the metalorganic framework of the MOF composite. MOF composites that can besynthesized in accordance with the present invention are not limited.MOF composites include, but are not limited to, for example, core-shellMOF composites; yolk-shell MOF composites; segmented MOF composites;doped MOF composites; mixed-metal (heterometallic) MOF composites; andmixed-linker MOF composites.

Exemplary MOF composites synthesized in accordance with the presentinvention include, for example, core shell composites including, forexample, Ni-MOF-74 (shell)/carbon (core); Ni-MOF-74 (shell)/Cr-MIL-101(core); Ni-MOF-74 (shell)/Co-MOF-74 (core); Ni-MOF-74(shell)/MIL-53(core); and mixed-metal MOF composites including, for example,Ni—Zn-MOF-74. However, the invention is not intended to be limited tothese exemplary MOF composites, as demonstrated further herein. Thefollowing Table 2 lists exemplary MOF composites with exemplaryprecursors.

MOF Composite Precursors [Ratio] Solvents [Ratio] Core-Shell orYolk-Shell MOF Composites Various MOFs (shell); [Core: activated carbon,Solvent combinations Carbon (core) carbon fibers, carbon from TABLE 1.nanotubes, porous carbon, or graphene oxide] [Shell: MOF precursors]Various MOFs (shell); [Core: metals, metal Solvent combinations Metalsor Metal oxides oxides, metal from TABLE 1. (core) nanoclusters] [Shell:MOF precursors] Various MOFs (shell); [Core: pre-synthesized Solventcombinations Pre-synthesized MOFs MOFs particles] from TABLE 1. (core)[Shell: MOF precursors] Various MOFs (shell); [Core: gypsum particles]Solvent combinations gypsum (core) [Shell: MOF precursors] from TABLE 1.Exemplary MOF Composites M-MOF-74 (shell); [Core: Iron oxide or Formetal nitrate: Iron oxide, gypsum, or gypsum] DMF:EtOH:H₂O [1:1:1]activated carbon (core); [Shell: DHTA:Metal For metal acetate: (M = Ni,Co, Zn, Mg, nitrate/acetate] [1:2] THF:H₂O [1:1] Cu, Fe, and Mn)M-MOF-74 (shell); [Core: MIL-101] For metal nitrate: Cr-MIL-101(core);[Shell: DHTA:Metal DMF:EtOH:H₂O [1:1:1] (M = Ni, Co, Zn, Mg, Cu,nitrate/acetate] [1:2] For metal acetate: Fe, Mn) THF:H₂O [1:1]M₁-MOF-74 (shell); [Core: Co-MOF-74] For metal nitrate: M₂-MOF-74 (core)[Shell: DHTA:Metal DMF:EtOH:H₂O [1:1:1] (M₁ and M₂ = Ni, Co,nitrate/acetate] [1:2] For metal acetate: Zn, Mg, Cu, Fe, Mn) THF:H₂O[1:1] M-MOF-74(shell); [Core: MIL-53] For metal nitrate: MIL-53 (core)[Shell: DHTA:Metal DMF:EtOH:H₂O [1:1:1] (M = Ni, Co, Zn, Mg,nitrate/acetate] [1:2] For metal acetate: Cu, Fe, Mn) THF:H₂O [1:1]Mixed-Metal MOF Composites M₁-M₂-MOF-74 [DHTA:Metal For metal nitrate:(M₁-M₂ = Ni, Co, Zn, nitrate/acetate] [1:2] DMF:EtOH:H₂O [1:1:1] Mg, Cu,Fe, and Mn) For metal acetate: THF:H₂O [1:1] Precursors: DHTA =DihydroxyTerepthalic Acid. Solvents: DMF = N,N-dimethylformamide; DEF =N,N-diethylfromamide; EtOH = ethanol; H₂O = water; THF =Tetrahydrofuran.

FIG. 7A is a pictograph illustrating an exemplary core-shell MOFcomposite of the present invention. The MOF composite includes a carboncore and a shell of a nickel-containing MOF (i.e., Ni-MOF-74). The shellof the MOF composite may include any number of shell layers, from one tomany. MOF core-shell composites synthesized in accordance with thepresent invention may be characterized using various analyticaltechniques including, for example, powdered X-ray Diffraction (XRD)analysis, Scanning-Electron Microscopic imaging (SEM), Energy-DispersiveX-ray (EDX) analysis as detailed hereafter. FIGS. 7B-7D show XRD resultsfor the components of the MOF composite illustrated in FIG. 7A. Forexample, FIG. 7B shows XRD results for pure carbon. FIG. 7C shows XRDresults for the pure nickel-metal MOF (Ni-MOF-74). And, FIG. 7D showsXRD results for the MOF composite that shows the composite includes boththe (Ni) metal of the pure Ni-containing MOF of the shell and the carbon(C) within the core as structural (crystalline) components of the MOFcomposite. FIG. 7E presents an SEM image of the exemplary core-shell MOFcomposite of FIG. 7A showing the target location of probe beams for asubsequent EDX analysis described hereafter. The SEM image shows thatthe Ni-MOF-74 shell formed atop the carbon core. FIG. 7F presents EDXresults for the Ni-MOF-74 shell at the target location of the MOFcomposite showing the presence of Ni metal. FIG. 7G presents EDX datafor the core of the MOF composite showing the presence of ahigh-intensity signal peak for carbon indicating presence of carbonwithin the core of the MOF composite.

FIG. 8A is a pictograph illustrating another exemplary core-shell MOFcomposite created under the process of the present invention. Thecomposite includes a core comprised of a first chromium (Cr)-containingMOF (e.g., Cr-MIL-101), and a second Ni-containing MOF (e.g., Ni-MOF-74)as the shell of the MOF composite. The pictograph again illustrates thatthe MOF composite may contain any number of shell layers, from one tomany. FIG. 8B presents powdered XRD data for the MOF composite of FIG.8A showing presence of crystalline phases for both the core (e.g.,Cr-MIL-101) and shell (e.g., Ni-MOF-74) of the MOF composite. FIG. 8Cshows an SEM image of the MOF composite of FIG. 8A showing both the coreand the shell, and the target location for the probe beam for an EDXanalysis described hereafter. FIG. 8D presents EDX results for thecomposite of FIG. 8A showing the presence of both Cr metal in the coreand Ni metal in the shell of the composite with their correspondingsignal intensities demonstrating proper formation of the MOF composite.

FIG. 9 presents EDX data for yet another exemplary core-shell MOFcomposite of the present invention. The MOF includes a core of a cobalt(Co)-containing MOF (e.g., Co-MOF-74) and a shell of Ni-MOF-74. EDX datashow both the presence of the Co metal in the core and the Ni metal inthe shell of the composite with their respective signal intensitiesdemonstrating the formation of the MOF composite.

FIG. 10A presents an SEM image for still yet another exemplarycore-shell MOF composite of the present invention. The MOF compositeincludes a core of an aluminum (AD-containing MOF (e.g., MIL-53), and ashell of Ni-MOF-74. The SEM image also shows the target location of theprobe beam for the EDX analysis described hereafter. FIG. 10B presentsdata from the EDX analysis of the composite of FIG. 10A. Data show thecomposite includes both Ni metal in the shell layer of the composite andAl metal in the core of the composite with their respective signalintensities demonstrating the formation of the MOF composite.

FIG. 11A presents powdered XRD data for exemplary mixed-metal MOFcomposites of the present invention including a Ni—Zn-MOF-74 compositeand a Ni—Co-MOF 74 composite, along with the respective pure metal MOFsfrom which the composites were synthesized. Data show the mixed-metalMOF structure includes the pure metal MOFs as components, e.g.,Ni-MOF-74, Zn-MOF-74, and Co-MOF-74. FIG. 11B shows an SEM image of amixed-metal composite comprised of a Ni—Zn-MOF-74 MOF and a Ni—Co-MOF-74MOF described previously in reference to FIG. 11A. FIGS. 11C-11D showelectronic mapping images for each of the nickel (Ni) and zinc (Zn)metals in the mixed-metal composite of FIG. 11B. Images show that the Niand Zn metals are distributed uniformly in the structure includingsurfaces of the MOF composite. FIG. 11E presents EDX data for theNi—Zn-MOF-74 mixed-metal composite of FIG. 11B. Data show the presenceof both the Ni and Zn metals in the structure of the composite withtheir respective signal intensities demonstrating the formation of theMOF composite.

Properties of MOFs and MOF composites of the present invention weretested. FIG. 12 compares water sorption (uptake) capacities for anexemplary Ni-MOF-74 product synthesized in accordance with the presentinvention and a MOF made by conventional liquid batch (i.e.,solvo-thermal) processing. The MPR-synthesized Ni-MOF-74 productexhibits a superior capacity for adsorption of water at all relativehumidity values compared to the batch-synthesized MOF product. Resultsare attributed at least in part to removal of precursor solvents frompores of nanoscale MOF seed particles immediately upon formation of theparticles in the MPR. Unavailability of excess solvent and reactantsduring formation of the MOF particles yields high purity MOFs in thereactor.

FIG. 13 compares CO₂ gas sorption capacity for the Ni-MOF-74 product ofthe present invention and the liquid batch MOF. Results again show theMPR-synthesized Ni-MOF-74 product exhibits a superior capacity for CO₂adsorption at all gas pressures compared to the batch-synthesized MOFproduct. Other MOFs prepared by the present invention perform similarly.In general, data indicate that MPR-synthesized MOFs and MOF compositesexhibit routinely better properties on average than those synthesized byconventional liquid batch processing.

The examples that follow that provide a further understanding of theinvention.

Example 1

An exemplary pure MOF, Ni-MOF-74, was synthesized as follows. A MOFprecursor solution was prepared by dissolving 30 mmol (e.g., 7.5 g) of ametal precursor containing nickel(II) acetate tetrahydrate in 100 mLwater and sonicating for 3 minutes to form a clear solution. A secondsolution was prepared by mixing 15 mmol (e.g., 3 g)2,5-dihydroxyterephthalic acid as an organic linker in 100 mL THFsolvent and sonicated for 5 min to form a clear solution. The aqueousnickel acetate solution was mixed with THF solution in a [1:1] ratio andsonicated for 3 to 10 minutes to form a clear MOF precursor solution.The MOF production reactor was preheated to a temperature of betweenabout 125° C. to about 150° C. The MOF precursor solution was thenintroduced into the MPR with a nitrogen carrier gas through a heatedinlet at a flow rate of between about 0.05 scfm to 2.0 scfm to form aplume of aerosolized liquid droplets (e.g., of a nanometer size).Pressure in the MPR was less than or equal to about 20 psi duringoperation. Size of resulting MOF particles was selected by controllingsuspension of the MOF particles with the carrier gas and/or recycledsolvents in MPR by varying gas flow rates as needed. Resulting MOFparticles were separated from the reactor using a cyclone separator.Yield of pure Ni-MOF-74 was greater than 85%. Production quantity was 1kilogram per day. Greater yields may be obtained with furtheroptimization.

Example 2

Pure metal MOFs including a cobalt metal MOF (Co-MOF-74); a zinc metalMOF (Zn-MOF-74); and a magnesium metal MOF (Mg-MOF-74) were producedusing precursor solutions containing selected metal nitrates or metalacetates as the metal source and selected organic linkers listed inTABLE 1. MOF precursor solutions were introduced into MPR at a synthesistemperature of about 150° C. First run yield of the Co-MOF-74(unoptimized) was 52%. Other pure MOFs listed in TABLE 1 were preparedusing different solvents and molar ratios including, for example,IRMOF-3 at a synthesis temperature of 165° C. [first run yield, ˜45%(unoptimized)]; IRMOF-9 at a synthesis temperature of 165° C. [first runyield, 50% (unoptimized)]. Yields greater than 85% were typical. Greateryields may be obtained with further optimization. Other MOFs can besimilarly produced including, for example, Mn-MOF-74, Fe-MOF-74,Ti-MOF-74, MOF-5, MOF-177, MOF-180, MOF-200, MOF-210, ZIF-8, TetZB,MOF-801, MOF-841, U10-66, U10-67, U10-68, NU-100, NU-1000, MIL-53,MIL-100, and MIL-101.

Example 3

A MOF precursor solution was prepared by dissolving a metal precursor ofcopper nitrate nonahydrate (2 mmol) in 100 mL DMF:ethanol:water in a[1:1:1] and sonicated for 3 minutes to form a clear solution. A secondsolution was prepared by mixing (1 mmol) benzene tricarboxylic acid asan organic linker in 100 mL DMF:ethanol:water in a [1:1:1] ratio andsonicated for 5 min to form a clear solution. Solutions were mixed andsonicated for 3 to 10 minutes to form a clear MOF precursor solution.The MOF production reactor was preheated to a temperature of betweenabout 125° C. to about 160° C. MOF precursor solution was thenintroduced into the MPR with a nitrogen carrier gas through a heatedinlet at a flow rate of between 0.05 scfm to 2.0 scfm to form a plume ofaerosolized liquid droplets of a nanometer size. The process wascontinued until the desired particle size was reached. Size of resultingMOF particles was selected by controlling suspension of the MOFparticles in the carrier gas and/or any recycled solvents. Resulting MOFparticles were separated from the MPR using a cyclone separator. Yieldof pure Cu-MOF-199 (HKUST-1) was 80%. Greater yields may be obtainedwith further optimization.

Example 4

Carbon was sieved to a particle size from about 20 μm to about 50 μm.Typical gravimetric ratios of carbon to MOF of up to 30 wt % (using theexpected yield of the MOF product for calculation purposes), with amaximum of up to about 50 wt %, were introduced into the MPR at atemperature of 150° C. (a known maximum yield temperature) and suspendedwith nitrogen carrier gas flowing at a rate between about 0.5 scfm toabout 2.0 scfm. The nickel MOF precursor solution for Ni-MOF-74 was thenintroduced into MPR. After 30 minutes, flow of MOF precursor solutionwas stopped and only carrier gas was introduced into MPR for 10 minutesto densify formed MOF particles in the reactor. MOF precursor solutionwas then again introduced. The process was continued until the desiredparticle size was reached. Size of resulting MOF composite particles wasselected to incorporate the core carbon particles by controllingsuspension of the resulting MOF particles in the carrier gas. Particleswere separated from the reactor using a cyclone separator. Productionquantity was 1 kilogram per day. An unoptimized yield of the core-shellcomposite was 80%. Greater yields may be obtained with furtheroptimization.

Example 5

A MOF precursor solution was prepared by dissolving 1 mmol (˜0.2 g) ofnickel silicofluoride (NiSiF6) in 50 mL ethanol and sonicating for 3minutes to form a clear solution. A second solution was prepared bymixing 2 mmol (˜0.16 g) of pyrazine in another 50 mL of ethanol to forma solution. Solutions were mixed and sonicated for 3 to 10 minutes toform a clear MOF precursor solution. MPR was preheated to a temperatureof between about 100° C. to about 125° C. MOF precursor solution wasthen introduced into the MPR with a nitrogen carrier gas to form a plumeof aerosolized liquid droplets of a nanometer size. Size of resultingMOF particles were selected by controlling suspension of the MOFparticles in the carrier gas and any recycled solvents. Particles wereseparated from the reactor using a cyclone separator. An alternate puremetal MOF, SIFSIX-3-Co, can be similarly produced.

Example 6

The MPR of FIG. 1 was used. An exemplary mixed metal MOF, Ni—Co-MOF-74,was synthesized as follows. MOF precursor solutions were prepared bydissolving 5 mmol each of a metal precursor nickel(II) acetatetetrahydrate and cobalt acetate tetrahydrate in 100 mL water andsonicating for 3 minutes to form a clear solution. A second solution wasprepared by mixing 5 mmol 2,5-dihydroxyterephthalic acid as an organiclinker in 100 mL THF solvent and sonicating for 5 min to form a clearsolution. Nickel acetate and cobalt acetate solutions were mixed withTHF solution in a 1:1 ratio and sonicated for 3 to 10 minutes to form aclear MOF precursor solution. MPR was preheated to a temperature ofbetween about 125° C. to about 150° C. MOF precursor solution was thenintroduced into the MPR with a nitrogen carrier gas to form a plume ofaerosolized liquid droplets of a nanometer size. Unoptimized yield ofthe Ni—Co-MOF-74 MOF composite was 60%. Yields 85% may be expected withfurther optimization. Alternate mixed-metal MOFs can be similarlyproduced including, for example, Ni—Zn-MOF-74 and Co—Zn-MOF-74. Nolimitations are intended.

Example 7

The MPR of FIG. 1 can be used to synthesize exemplary doped or segmentedMOF composites composed of two, three, or more components in accordancewith the procedure of EXAMPLE 1 and EXAMPLE 2. In one example, a dopedMOF composite can include a first component composed of a quantum dot(QD) material such as a nanoscale particles of semiconducting materials;carbon materials such as carbon nanotubes, carbon nanofibers; grapheneoxide; polymers or metal oxides as a second component; and a MOF as athird component. Component concentrations can be varied as needed toachieve the desired amount of doping in the resulting MOF product. Inthis example, all three components can be introduced simultaneously andcontinuously into the MPR in separate MOF precursor solutions andaerosolized separately using three different injectors each with a flowof carrier gas into the MPR. Optionally, flows of precursor solutionscan be stopped after a selected run time (e.g., 30 minutes) withresulting doped MOFs optionally suspended in the carrier gas for aselected time (e.g., 10 minutes) to densify the particles. Quantities ofeach component in the MOF composite can be adjusted as needed to formthe desired doping in the MOF composite. Flow of carrier gases can alsobe adjusted to provide suspension of particles in the MPR that achievedselected MOF particle sizes or particle weights. This example isexpected to produce a quantity of doped MOF composites of about 1kilogram per day.

The method and process of the present invention provides continuousaerosolized formation of MOFs and MOF composites that is rapid andcontrolled. MOFs and MOF composites of the present invention are fullyactivated immediately following formation so do not need furthertreatment to remove contaminates. As such, resulting MOFs and MOFcomposites also have a high purity. Elimination of conventional solventexchange following synthesis is cost-effective and saves time. Thepresent invention also permits recycling of solvents used in MOFsynthesis which reduces MOF production costs by up to 50%. In general,MOFs and MOF composites also exhibit enhanced properties compared totheir batch synthesized counterparts. The present invention thus yieldsscalable quantities and yields of the MOFs and MOF composites and allowsnew MOF materials to be synthesized that were previously difficult orcostly to synthesize.

Applications

MOFs and MOF composites of the present invention find application in gasstorage; gas purification; gas and vapor sorption; gas separation;molecular separation; catalysis; heterogeneous catalysis; sensors andsensor applications; adsorption devices; chillers; formation offunctional membranes; formation of thin films; production ofpharmaceuticals and other specialty materials; and drug delivery. Thesystems and processes of the present invention allow these MOFs to bereliably, effectively and efficiently created.

While exemplary embodiments of the present invention have been shown anddescribed, it will be apparent to those skilled in the art that manychanges and modifications may be made without departing from theinvention in its true scope and broader aspects. The appended claims aretherefore intended to cover all such changes and modifications as fallwithin the spirit and scope of the invention.

What is claimed is:
 1. A method for making Metal Organic Framework (MOF)materials including MOF composites, the method comprising the step of:injecting aerosolized MOF precursors into a fluidized bed reactor at apreselected temperature.
 2. The method of claim 1 further comprising thestep of simultaneously evaporating solvent within the reactor.
 3. Themethod of claim 2 further comprising the step of ultrasonicallyaerosolizing the MOF precursors.
 4. The method of claim 3 furthercomprising the step of raising the temperature in the reactor at the endof the desired synthesis to remove solvents and densify the MOFmaterial.
 5. The method of claim 1, further comprising the step ofrecovering solvents from the reaction chamber and recycling same for usetherein.
 6. The method of claim 1, further including introducing a freshquantity of aerosolized MOF precursor droplets continuously into thefluid volume.
 7. The method of claim 1, wherein the MOF precursorsinclude one or more metals selected from the group consisting of: Ti, V,Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Os, Rh, Pd, Ag, Au,Cd, Ir, Pt and combinations thereof.
 8. The method of claim 1, whereinthe MOF precursors include an organic linker selected from an arylorganic acid; an aryl alcohol; an aryl carboxylic acid; an aryl hydroxylcarboxylic acid; di-substitution products, tri-substitution products,and tetra-substitution products thereof; or combinations thereof.
 9. Themethod of claim 1, wherein the size of the MOF or MOF composite isbetween about 50 μm to about 1500 μm.
 10. A method of making a MetalOrganic Framework (MOF) or a MOF composite, comprising the steps of:introducing a plume of aerosolized liquid droplets of a MOF precursorsolution of a selected size in a carrier gas into a fluidized bedreaction chamber; and circulating the aerosolized liquid droplets in thefluid volume at a temperature above ambient to release solventstherefrom and form solid particles of the MOF or MOF composite of aselected size.
 11. The method of claim 10, further comprising the stepsof repeating the wherein the introducing and circulating steps areperformed iteratively including introducing a fresh quantity ofaerosolized MOF precursor droplets continuously into the reactionchamber to increase the size of the resulting solid particles.
 12. Asystem for forming a Metal-Organic Framework (MOF) materials includingMOF composites, the system comprising: a MOF production reactor defininga fluidized bed reaction chamber configured to receive a plume ofaerosolized liquid MOF precursor droplets in a carrier gas therein for atime sufficient to form solid particles of the MOF or MOF composite of aselected size therein.
 13. The system of claim 12, further comprising aheating device to alternatively raise and lower the temperature withinthe reaction chamber.
 14. The system of claim 12 further comprising anultrasonic aerosolization device.
 15. The system of claim 12 furthercomprising a de-entrainment chamber configured to remove and collectsolvents from the aerosolized MOF precursor droplets.
 16. The system ofclaim 12, further including a separation and recirculation deviceconfigured to collect the solid particles at the selected size from theMOF production reactor and to return the solid particles smaller that apreselected size back into the reaction chamber.
 17. A MOF compositematerial comprising a core having at least one layer containing a MOFmaterial covering said core.